I’m a fan of Arby’s Reuben. Very solid for fast food. If you can find a store that properly toasts the bread on the griddle, they’re excellent.
I get the Turkey Reuben (available on request).
If you have a Culvers around, their reuben is also quite a bit above average. Especially for a bigger chain.
My buddy loves their Cod (or is it Haddock) sandwich. Others have also claimed they are very good. I don’t do fish, so can’t comment.